Telephone-exchange system.



E..E. HINRICHSEN. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAY I9. 915.

Patented June 26; 1917.

v /n vefllor: [dward f. Hinr/chsen.

EDWARD E. HINRICHSEN, or NEW YORK, N. Y., Ass-I'GNoR, BY MEsNE As's'IGNME'NT's, 'ro' WESTERN ELECTRIC COMPANY, INCORPORATED, A CQRECRATICN OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed May 19, 1915.

T all whom it may concern:

Be it known that I, EDWARD E. HINRlCI-I- SEN, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone eX- change systems of the central energy type, and particularly to systems of this class in which a special class of service involves the use of a flashing signal.

The object of this invention is to provide a simple equipment in connection with such systems for obtaining a flashing signal, which equipment will be economical to install and maintain. In exchanges previously prox'ided with such equipment, the means for flashing the signaling device has involved the use of a continuously operating interrupter which is too expensive both from a first cost and maintenance standpoint to warrant its use in connection with small equipments.

In accordance With this invention there is provided a. simple, compact and reliable form of interrupting means which operates automatically upon the connection of a signaling device thereto.

This invention is illustrated in the accompanying drawing in which all apparatus is shown in its normal and unactuated condition.

There is shown in the drawing a telephone exchange system containing one embodiment of this invention and comprising the usual subscribers stations A and B and a cord circuit C, located at a central ofiice, for interconnecting the subscribers stations. It is believed that this invention will be fully understood from a description of the operation of the system shown in the drawing, and it will be so described.

Subscriber A wishing to converse with subscriber B signals the operator in the usual manner. The operator, answering, inserts an answering plug in thejack of the calling line, causing the operation of relay and cutoff relay 6. The operation of relay 5 lights supervisory lamp 16, and causes relay 7 to operate over a circuit, which may be traced from battery 8 through the Winding of relay 7 and itsnormally closed contact, contact 9 of relay 10, and contact 11 of Specification of Letters Patent.

. circuit.

Patented James, 1917.

Serial No. 29,079.

relay 5 to ground. The operationof relay 7 completes a locking circuit for itself. The operation of the cutoff relay 6 completes the line circuit to the ack, whereupon relay is operated. The operation of relay 1O extinguishes the lamp 16 and connects a circuit interrupting device 4 in circuit therewith. The circuit interrupting device 4:, comprising a plurality of interconnected re lays 17, 18 and 19, is normally inactive, but when connected in circuit with the lamp 16 and a source of current it becomes active, thereby interrupting the lamp circuit, caning the lamp to be lighted intermittently to furnish a characteristic signal to the operator. The circuit which includes the signal lamp 16 and the interrupting device 1 may be traced from battery through the lamp 16, contact 20 of relay 10, contact 21 of relay 7, the winding of pilot relay 22, the winding of relay 17 and contact 23 of relay 19 to ground. Relay 17 operates closing its contact 24, whereupon relay 18 operates closing its contact 25. The closure of contact 25 causes the operation of relay 19 and in turn opens the circuit of relay 17 and signal lamp 16. Relays 18 and 19 release in turn, completing the lamp circuit. As long as the interrupting device 4 is connected in circuit with the lamp 16 and a source of current, relays 17, 18 and 19 will continue to be operated and released in the order hereinbefore referred to, thereby intermittently lighting the lamp 16. Since the pilot relay '22 is in circuit with the interrupting device, pilot signal 26 will be lighted intermittently.

The operator now actuates the listening key 30 connecting the operators telephone set across the talking strands of the cord In the operation of key 30 a contact in the locking circuit of relay 7 is opened, whereupon relay 7 releases, opening the circuit which includes supervisory signal 16 and the interrupting device 4. The signal thereupon becomes inert and the interrupter becomes inactive. The operator, finding that subscriber B is wanted, restores listening key 30 to its normal position and inserts the calling plug in the jack of the subscriber Bs line, causing thereby theoperation of relay and cutoff relay 36. Relay 35 in operating causes the operation of supervisory signal 37 and also causes, in a manner well understood, the automatic application of a source of ringing current 38 to the called line for operating a call signal loo bell 39. Subscriber B in responding removes the receiver from the switchhook, thereby causing, in a manner Well understood, the disconnection of the ringing current from the line, after which calling supervisory re-- lay 10 is operated, efiacing calling supervisory signal 37.

Upon finishing the conversation subscribers A and B restore their respective receivers to the switchhooks, whereupon relays 10 and 4.0 release, permitting supervisory signals 16 and 37 to operate to give disconnect signals. If the operator is not busy, both plugs are removed from the jacks and all apparatus returns to normal. However, should the operator be busy and, furthermore, should subscriber A desire to immediately make another call, the receiver at station A is again removed from the switchhook, thereby causing the supervisory signal 16 and the pilot signal. 26 to automatically flash to furnish to the operator a recall signal.

As before stated, when the receiver at station A is restored to the switchhook, relay 1O releases. The release of this relay completes the energizing circuit for relay 7 which, upon operating, establishes the locking circuit for itself. Thereafter upon the removal of the receiver from the switchhook, relay 10 operates and connects the interrupting device 1 in circuit with the supervisory lamp 16, whereupon the interrupting device becomes active and causes the supervisory signals 16 and pilot signal 26 to flash intermittently. The operator, observing the flashing signal or signals, operates listening key 80, whereupon the signals are retired and the interrupting device is rendered inactive. The operator may now communicate with the subscriber at station A to determine his wants.

It will be understood from the foregoing description that this invention provides an improved signaling scheme in connection with telephone exchange systems, in which the interrupting device for causing the supervisory signal to flash intermittently is very simple, efficient, positive in operation and inexpensive. Furthermore, such an interrupting device when not in circuit with the signaling device is inactive, thereby re ducing the current consumption to a minimum. Such an interruptingdevice has another advantage, namely, that it is self-starting upon being connected in circuit with the signaling device. Such an arrangement provides for a minimum number of relays and contacts in the system. The circuit interrupting device 4 is common to the telephone exchange.

What is claimed is:

1. A telephone exchange system comprising telephone lines terminating at a central Copies of this patent may be obtained for office, a link circuit thereat connected with the telephone line, a signaling device for the link circuit, a supervisory 'relay in the link circuit, a second relay energizing upon the deenergization of the supervisory relay, a circuit for the signaling device completed upon the subsequent energization of the supervisory relay while the second relay is energized, and a plurality of relays energized seriatim upon the completion of the circuit to open the circuit and then deenergized scriatim upon the opening thereof to again close the circuit.

2. A telephone exchange system comprising telephone lines terminating at a central ofiice, a link circuit thercat connected with the telephone line, a signaling device for the link circuit, a supervisory relay in the link circuit, a second relay responsive to the deenergization of the supervisory relay, a circuit for the signaling device completed upon the response of the second relay and the subsequent energization of the supervisory relay, a third relay in the circuit energized upon the completion thereof, and a plurality of relays energized scriatim upon the energization of the third relay to open the circuit and then deenergized seriatv'm upon the resulting deiinergization of the third relay to close the circuit.

3. A telephone exchange system comprising a telephone line terminating at a central office, a link circuit thereat connected with the telephone line, a signaling device in the link circuit, a relay responsive to the opening of the telephone line, a circuit for the signaling device completed upon the response of the relay and the subsequent closing of the telephone line, a second relay in the circuit energized upon the completion. thereof, and a plurality of relays energized seriatim upon the energization of the second relay to open the circuit and then deenergized sericttz'm upon the resulting deene'rgization of the second. relay to close the circuit.

4. A telephone exchange system comprising a telephone line terminating at a central office, a link circuit thereat connected with the telephone line, a signaling device in the link circuit, a relay responsive to the opening of the telephone line, a circuit for the signaling device completed upon the re-' sponse of the relay and the subsequent closing of the telephone line, and a plurality of relays energized seriazfim upon the completion of the circuit to open the circuit and them deenergized scrim 2m upon the opening thereof to again close the circuit.

In witness whereof, I hereunto subscribe my name this 18th day of May, A. D., 1915.

EDWARD E. HINRIGHSEN.

five cents each, by addressing the Commissioner of latents,

, Washingtou,D.G. "j, V 

